In conventional manner, such a device comprises a plurality of tightening spindles rotated by a drive member via adjustable torque-limiting transmission devices so that bottles of various types requiring their caps to be tightened to a greater or lesser extent without running the risk of damaging the bottles can be closed optimally.
In known tightening devices, the torque-limiting transmission devices comprise a first transmission member, a second transmission member mounted coaxially with the first transmission member to rotate relative thereto between an abutment fixed to the first transmission member and a thrust member constrained to rotate with the first transmission member and movable relative thereto in a direction parallel to an axis of rotation of the transmission members, at least one torque-limiting member being disposed between the second transmission member and the abutment or thrust member, and an adjustable resilient member carried by the first transmission member and acting on the thrust member in a direction tending to urge it towards the abutment. When an installation includes a plurality of tightening spindles, each associated with a transmission device, it is necessary to adjust each of the transmission devices individually each time the type of bottle or the type of cap is changed. This adjustment operation is fiddly and considerably reduces the throughput of the tightening installation. In addition, given the rate at which tightening machines operate, it is generally not possible to perform this adjustment while the machine is in operation, thereby requiring the machine to be stopped. Further, each time an adjustment is performed, it is necessary to perform the adjustment by adapting it to characteristics specific to each transmission device, in particular the wear of the torque-limiting member.
An object of the invention is to propose a tightening device capable of two adjustments: one of the adjustments being intended to match the torque-limiting characteristics of the various transmission devices in an installation, while the second adjustment is performed identically on all of the transmission devices in order to adapt them to a particular type of cap or a particular type of bottle.
Another object of the present invention is to provide a tightening device comprising a plurality of tightening spindles in which the tightening torque of the set of spindles can be changed by a single adjustment operation.